Most currently installed video surveillance and monitoring systems are based on NTSC/PAL/SECAM analog video cameras, with camera resolution rigidly fixed by the corresponding video standard. Thus, to inspect fine detail of the scene, NTSC surveillance systems have to rely on expensive optical zoom and mechanical pan and tilt. However, higher optical zoom inevitably corresponds to reduced field of view of the camera, requiring the operator to make a choice between higher level of detail and higher coverage of the area under surveillance. Furthermore, the actuators responsible for mechanical pan, tilt and zoom are typically slow as compared with the camera frame-rate. This makes zooming on rapidly moving targets, such as license plates of the moving automobile, difficult if not impossible.
In contrast to NTSC-based video, network cameras are not restricted to the specific resolution and frame rate and are primarily limited by the on-camera computational resources and available network bandwidth. Network video cameras rely on packet-oriented digital image transmission are not limited to any particular image resolution and frame rate. This opens the door for the development of high-resolution video surveillance systems that are overall superior to existing NTSC systems and provide video-rate multi-format functionality and instantaneous pan, tilt and zoom capability, previously unavailable in video surveillance.
However, to produce multi-megapixel imagery at video rates, the network camera has to be able to perform image processing, compression and network transmission at vastly higher data bandwidths than are typical for NTSC cameras. Conventional approach of implementing image processing, compression and network protocols in general purpose DSPs and microprocessors significantly limits overall camera bandwidth necessitating the trade-offs between camera frame-rate and resolution.